Problem: Constraints

* H is an integer between 2 and 50 (inclusive).
* W is an integer between 2 and 50 (inclusive).
* s_{i, j} is `.` or `#` (1 \leq i \leq H, 1 \leq j \leq W).
* s_{1, 1} and s_{H, W} are `.`.

Input

Input is given from Standard Input in the following format:


H W
s_{1, 1}s_{1, 2}s_{1, 3} ... s_{1, W}
s_{2, 1}s_{2, 2}s_{2, 3} ... s_{2, W}
:   :
s_{H, 1}s_{H, 2}s_{H, 3} ... s_{H, W}


Output

Print the maximum possible score that Snuke can achieve, or print -1 if the game cannot be completed.

Examples

Input

3 3
..#
#..
...


Output

2


Input

3 3
..#
..
...


Output

2


Input

10 37
.....................................
...#...####...####..###...###...###..
..#.#..#...#.##....#...#.#...#.#...#.
..#.#..#...#.#.....#...#.#...#.#...#.
.#...#.#..##.#.....#...#.#.###.#.###.
.#####.####..#.....#...#..##....##...
.#...#.#...#.#.....#...#.#...#.#...#.
.#...#.#...#.##....#...#.#...#.#...#.
.#...#.####...####..###...###...###..
.....................................


Output

209

Solution (in PYTHON3):

Solution:
h,w=map(int,input().split())
maze=[list(input()) for _ in range(h)]
dx=[1,0,-1,0]
dy=[0,1,0,-1]
queue=[]
ans = 0
cn = 0
for i in maze:
     cn += i.count("#")
queue.append([0,0,0])
while len(queue)>0:
    x,y,cnt=queue.pop(0)
    ans=cnt
    if x == h - 1 and y == w - 1:
        print(h*w-ans-cn-1)
        exit()
    for i in range(4):
        X=x+dx[i]
        Y = y + dy[i]
        if not (0 <= X < h and 0 <= Y < w):
             continue
        if maze[X][Y]=="#":
            continue
        if maze[X][Y]==".":
            queue.append([X,Y,cnt+1])
            maze[X][Y]="#"
print(-1)